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Results for “HALIDES”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Thermal multiferroics in all-inorganic quasi-two-dimensional halide perovskites
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Probing photoelectrical transport in lead halide perovskites with van der Waals contacts
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Metal halide perovskite nanostructures for optoelectronic applications and the study of physical properties
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Confinement of atomically defined metal halide sheets in a metal-organic framework
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Single-photon superradiance in individual caesium lead halide quantum dots
The brightness of an emitter is ultimately described by Fermi’s golden rule, with a radiative rate proportional to its oscillator strength times the local density of photonic states. As the oscillator strength is an intrinsic material property, the quest for ever brighter emission has relied on the local density of photonic states engineering, using dielectric or plasmonic resonators. By contrast, a much less explored avenue is to boost the oscillator strength, and hence the emission rate, using a collective behaviour termed superradiance. Recently, it was proposed that the latter can be realized using the giant oscillator-strength transitions of a weakly confined exciton in a quantum well when its coherent motion extends over many unit cells. Here we demonstrate single-photon superradiance in perovskite quantum dots with a sub-100 picosecond radiative decay time, almost as short as the reported exciton coherence time. The characteristic dependence of radiative rates on the size, composition and temperature of the quantum dot suggests the formation of giant transition dipoles, as confirmed by effective-mass calculations. The results aid in the development of ultrabright, coherent quantum light sources and attest that quantum effects, for example, single-photon emission, persist in nanoparticles ten times larger than the exciton Bohr radius.
Inorganic cesium lead mixed halide based perovskite solar materials modified with functional silver iodide
Inorganic CsPbIBr 2 perovskites have recently attracted enormous attention as a viable alternative material for optoelectronic applications due to their higher efficiency, thermal stability, suitable bandgap, and proper optical absorption. However, the CsPbIBr 2 perovskite films fabricated using a one-step deposition technique is usually comprised of small grain size with a large number of grain boundaries and compositional defects. In this work, silver iodide (AgI) will be incorporated as an additive into the CsPbIBr 2 perovskite precursor solution to prepare the unique perovskite CsI(PbBr 2 ) 1-x (AgI) x . The AgI additive in the precursor solution works as a nucleation promoter which will help the perovskite to grow and merge into a continuous film with reduced defects. With detailed characterizations, we found that incorporating AgI additive resulted in a uniform perovskite film with fewer grain boundaries, increased grain size, crystallinity, optical absorption while decreasing carrier recombination and trap density. Using the AgI in an optimum amount, we fabricated CsPbIBr 2 perovskite solar cells (PSCs) with a simple structure and achieved a power conversion efficiency (PCE) of 7.2% with a reduced hysteresis index. This work offers an alternative approach towards preparing high-quality CsPbIBr 2 perovskite films for solar cells with higher stability and other optoelectronic applications.
Sustainable lead management in halide perovskite solar cells
Despite the rapid development of perovskite solar cells (PSCs) toward commercialization, the toxic lead (Pb) ions in PSCs pose a potential threat to the environment, health and safety. Managing Pb via recycling represents a promising approach to mitigating its toxicity. However, managing Pb from commonly used organic solvents has been challenging due to the lack of suitable Pb adsorbents. Here, we report a new adsorbent for both separation and recovery of Pb from PSC pollutants. The synthesized iron-incorporated hydroxyapatite possesses a strongly negatively charged surface that improves electrostatic interaction through surface-charge delocalization, thus leading to enhanced Pb adsorption. Finally, we demonstrate the feasibility of a complete Pb management process, including the purification of Pb-containing non-aqueous solvents below 15 parts per 10 9 , a level compliant with the standards of the US Environmental Protection Agency, as well as recycling of 99.97% of Pb ions by forming lead iodide.
Direct visualization of radiation-induced transformations at alkali halide–air interfaces
Radiation driven reactions at mineral/air interfaces are important to the chemistry of the atmosphere, but experimental constraints (e.g. simultaneous irradiation, in situ observation, and environmental control) leave process understanding incomplete. Using a custom atomic force microscope equipped with an integrated X-ray source, transformation of potassium bromide surfaces to potassium nitrate by air radiolysis species was followed directly in situ at the nanoscale. Radiolysis initiates dynamic step edge dissolution, surface composition evolution, and ultimately nucleation and heteroepitaxial growth of potassium nitrate crystallites mediated by surface diffusion at rates controlled by adsorbed water. Finally, in contrast to in situ electron microscopy and synchrotron-based imaging techniques where high radiation doses are intrinsic, our approach illustrates the value of decoupling irradiation and the basis of observation.
Designing metal halide perovskite solar modules for thermomechanical reliability
There is a significant deficiency in perovskite solar module (PSM) stability under thermomechanical stressors which is not well-understood. In this perspective, common issues seen with perovskite solar cell device fabrication related to thermomechanical reliability of PSM processing are discussed, with a focus on how the robustness of device layers and interlayer adhesion can be improved. Film stresses, adhesion of charge transport layers, and instability under light and heat are discussed with the purpose of providing insight on designing PSMs for durability. Processing conditions of encapsulation of PSMs and critical parameters to consider are also examined, and accelerated testing protocols for PSMs are discussed that probe mechanical degradation modes and ensure reliability of devices in the field.
Organic-Inorganic Hybrid Lead Halide Perovskites for Optoelectronic and Electronic Applications
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Halide perovskite materials for solar cells: A theoretical review
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Facile Solvothermal Growth of Single Crystal Mixed Halide Perovskite CH3NH3Pb(Br1-xClx)3
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Syntheses, structures, and 1 H, 13 C{ 1 H} and 119 Sn{ 1 H} NMR chemical shifts of a family of trimethyltin alkoxide, amide, halide and cyclopentadienyl compounds
The synthesis and full characterization, including Nuclear Magnetic Resonance (NMR) data ( 1 H, 13 C{ 1 H} and 119 Sn{ 1 H}), for a series of Me 3 SnX (X = O-2,6-tBu 2 C 6 H 3 (1), (Me 3 Sn)N(2,6- i Pr 2 C 6 H 3 ) (3), NH-2,4,6- t Bu 3 C 6 H 2 (4), N(SiMe 3 ) 2 (5), NEt 2 , C 5 Me 5 (6), Cl, Br, I, and SnMe 3 ) compounds in benzene-d 6 , toluene-d 8 , dichloromethane-d 2 , chloroform-d 1 , acetonitrile-d 3 , and tetrahydrofuran-d 8 are reported. The X-ray crystal structures of Me 3 Sn(O-2,6- t Bu 2 C 6 H 3 ) (1), Me 3 Sn(O-2,6- i Pr 2 C 6 H 3 ) (2), and (Me 3 Sn)(NH-2,4,6- t Bu 3 C 6 H 2 ) (4) are also presented. As a result, these compiled data complement existing literature data and ease the characterization of these compounds by routine NMR experiments.